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Lin NH, Goh A, Lin SH, Chuang KA, Chang CH, Li MH, Lu CH, Chen WY, Wei PH, Pan IH, Perng MD, Wen SF. Neuroprotective Effects of a Multi-Herbal Extract on Axonal and Synaptic Disruption in Vitro and Cognitive Impairment in Vivo. J Alzheimers Dis Rep 2023; 7:51-76. [PMID: 36777330 PMCID: PMC9912829 DOI: 10.3233/adr-220056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 01/02/2023] [Indexed: 01/19/2023] Open
Abstract
Background Alzheimer's disease (AD) is a multifactorial disorder characterized by cognitive decline. Current available therapeutics for AD have limited clinical benefit. Therefore, preventive therapies for interrupting the development of AD are critically needed. Molecules targeting multifunction to interact with various pathlogical components have been considered to improve the therapeutic efficiency of AD. In particular, herbal medicines with multiplicity of actions produce cognitive benefits on AD. Bugu-M is a multi-herbal extract composed of Ganoderma lucidum (Antler form), Nelumbo nucifera Gaertn., Ziziphus jujuba Mill., and Dimocarpus longan, with the ability of its various components to confer resilience to cognitive deficits. Objective To evaluate the potential of Bugu-M on amyloid-β (Aβ) toxicity and its in vitro mechanisms and on in vivo cognitive function. Methods We illustrated the effect of Bugu-M on Aβ25-35-evoked toxicity as well as its possible mechanisms to diminish the pathogenesis of AD in rat cortical neurons. For cognitive function studies, 2-month-old female 3×Tg-AD mice were administered 400 mg/kg Bugu-M for 30 days. Behavioral tests were performed to assess the efficacy of Bugu-M on cognitive impairment. Results In primary cortical neuronal cultures, Bugu-M mitigated Aβ-evoked toxicity by reducing cytoskeletal aberrations and axonal disruption, restoring presynaptic and postsynaptic protein expression, suppressing mitochondrial damage and apoptotic signaling, and reserving neurogenic and neurotrophic factors. Importantly, 30-day administration of Bugu-M effectively prevented development of cognitive impairment in 3-month-old female 3×Tg-AD mice. Conclusion Bugu-M might be beneficial in delaying the progression of AD, and thus warrants consideration for its preventive potential for AD.
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Affiliation(s)
- Ni-Hsuan Lin
- Institute of Molecular Medicine, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan
| | - Angela Goh
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Shyh-Horng Lin
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Kai-An Chuang
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Chih-Hsuan Chang
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Ming-Han Li
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Chu-Hsun Lu
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Wen-Yin Chen
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Pei-Hsuan Wei
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - I-Hong Pan
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Ming-Der Perng
- Institute of Molecular Medicine, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan,
School of Medicine, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan,Correspondence to: Shu-Fang Wen, Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, 321, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan. Tel.: +886 35743946; E-mail: and Ming-Der Perng, College of Life Sciences, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan. Tel.: +886 35742024; E-mail:
| | - Shu-Fang Wen
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan,Correspondence to: Shu-Fang Wen, Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, 321, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan. Tel.: +886 35743946; E-mail: and Ming-Der Perng, College of Life Sciences, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan. Tel.: +886 35742024; E-mail:
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Saloner R, Fonseca C, Paolillo EW, Asken BM, Djukic NA, Lee S, Nilsson J, Brinkmalm A, Blennow K, Zetterberg H, Kramer JH, Casaletto KB. Combined Effects of Synaptic and Axonal Integrity on Longitudinal Gray Matter Atrophy in Cognitively Unimpaired Adults. Neurology 2022; 99:e2285-e2293. [PMID: 36041868 PMCID: PMC9694840 DOI: 10.1212/wnl.0000000000201165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/11/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND AND OBJECTIVES Synaptic dysfunction and degeneration is a predominant feature of brain aging, and synaptic preservation buffers against Alzheimer disease (AD) protein-related brain atrophy. We tested whether CSF synaptic protein concentrations similarly moderate the effects of axonal injury, indexed by CSF neurofilament light [NfL]), on brain atrophy in clinically normal adults. METHODS Clinically normal older adults enrolled in the observational Hillblom Aging Network study at the UCSF Memory and Aging Center completed baseline lumbar puncture and longitudinal brain MRI (mean scan [follow-up] = 2.6 [3.7 years]). CSF was assayed for synaptic proteins (synaptotagmin-1, synaptosomal-associated protein 25 [SNAP-25], neurogranin, growth-associated protein 43 [GAP-43]), axonal injury (NfL), and core AD biomarkers (ptau181/Aβ42 ratio; reflecting AD proteinopathy). Ten bilateral temporoparietal gray matter region of interest (ROIs) shown to be sensitive to clinical AD were summed to generate a composite temporoparietal ROI. Linear mixed-effects models tested statistical moderation of baseline synaptic proteins on baseline NfL-related temporoparietal trajectories, controlling for ptau181/Aβ42 ratios. RESULTS Forty-six clinically normal older adults (mean age = 70 years; 43% female) were included. Synaptic proteins exhibited small to medium correlations with NfL (r range: 0.10-0.36). Higher baseline NfL, but not ptau181/Aβ42 ratios, predicted steeper temporoparietal atrophy (NfL × time: β = -0.08, p < 0.001; ptau181/Aβ42 × time: β = -0.02, p = 0.31). SNAP-25, neurogranin, and GAP-43 significantly moderated NfL-related atrophy trajectories (-0.07 ≤ β's ≥ -0.06, p's < 0.05) such that NfL was associated with temporoparietal atrophy at high (more abnormal) but not low (more normal) synaptic protein concentrations. At high NfL concentrations, atrophy trajectories were 1.5-4.5 times weaker when synaptic protein concentrations were low (β range: -0.21 to -0.07) than high (β range: -0.33 to -0.30). DISCUSSION The association between baseline CSF NfL and longitudinal temporoparietal atrophy is accelerated by synaptic dysfunction and buffered by synaptic integrity. Beyond AD proteins, concurrent examination of in vivo axonal and synaptic biomarkers may improve detection of neural alterations that precede overt structural changes in AD-sensitive brain regions.
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Affiliation(s)
- Rowan Saloner
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China.
| | - Corrina Fonseca
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
| | - Emily W Paolillo
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
| | - Breton M Asken
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
| | - Nina A Djukic
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
| | - Shannon Lee
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
| | - Johanna Nilsson
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
| | - Ann Brinkmalm
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
| | - Kaj Blennow
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
| | - Henrik Zetterberg
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
| | - Joel H Kramer
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
| | - Kaitlin B Casaletto
- From the Department of Neurology (R.S., E.W.P., B.M.A., N.A.D., S.L., J.H.K., K.B.C.), Memory and Aging CenterWeill Institute for Neurosciences, University of California, San Francisco; Helen Wills Neuroscience Institute (C.F.), University of California, Berkeley; Department of Psychiatry and Neurochemistry (J.N., A.B., K.B., H.Z.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory (A.B., K.B., H.Z.), Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease (H.Z.), UCL Institute of Neurology, Queen Square, London, UK; UK Dementia Research Institute at UCL (H.Z.), London; and Hong Kong Center for Neurodegenerative Diseases (H.Z.), China
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Transport-dependent maturation of organelles in neurons. Curr Opin Cell Biol 2022; 78:102121. [PMID: 36030563 DOI: 10.1016/j.ceb.2022.102121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 07/15/2022] [Indexed: 01/31/2023]
Abstract
Some organelles show a spatial gradient of maturation along the neuronal process where more mature organelles are found closer to the cell body. This gradient is set up by progressive maturation steps that are aided by differential organelle distribution as well as transport. Autophagosomes and endosomes mature as they acquire lysosomal membrane proteins and decrease their luminal pH as they are retrogradely transported towards the cell body. The acquisition of lysosomal proteins along the neuronal processes likely occurs through fusion or membrane exchange events with Golgi-derived donor transport carriers that are transported anterogradely from the cell body. The mechanisms by which endosomes and autophagosomes mature might be applicable to other organelles that are transported along neuronal processes. Defects in axonal transport may also contribute to the accumulation of immature organelles in neurons. Such accumulations have been seen in neurons of neurodegenerative models.
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Salvadores N, Gerónimo-Olvera C, Court FA. Axonal Degeneration in AD: The Contribution of Aβ and Tau. Front Aging Neurosci 2020; 12:581767. [PMID: 33192476 PMCID: PMC7593241 DOI: 10.3389/fnagi.2020.581767] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 09/09/2020] [Indexed: 12/25/2022] Open
Abstract
Alzheimer's disease (AD) represents the most common age-related neurodegenerative disorder, affecting around 35 million people worldwide. Despite enormous efforts dedicated to AD research over decades, there is still no cure for the disease. Misfolding and accumulation of Aβ and tau proteins in the brain constitute a defining signature of AD neuropathology, and mounting evidence has documented a link between aggregation of these proteins and neuronal dysfunction. In this context, progressive axonal degeneration has been associated with early stages of AD and linked to Aβ and tau accumulation. As the axonal degeneration mechanism has been starting to be unveiled, it constitutes a promising target for neuroprotection in AD. A comprehensive understanding of the mechanism of axonal destruction in neurodegenerative conditions is therefore critical for the development of new therapies aimed to prevent axonal loss before irreversible neuronal death occurs in AD. Here, we review current evidence of the involvement of Aβ and tau pathologies in the activation of signaling cascades that can promote axonal demise.
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Affiliation(s)
- Natalia Salvadores
- Center for Integrative Biology, Faculty of Sciences, Universidad Mayor, Santiago, Chile.,Fondap Geroscience Center for Brain Health and Metabolism, Santiago, Chile
| | - Cristian Gerónimo-Olvera
- Center for Integrative Biology, Faculty of Sciences, Universidad Mayor, Santiago, Chile.,Fondap Geroscience Center for Brain Health and Metabolism, Santiago, Chile
| | - Felipe A Court
- Center for Integrative Biology, Faculty of Sciences, Universidad Mayor, Santiago, Chile.,Fondap Geroscience Center for Brain Health and Metabolism, Santiago, Chile.,Buck Institute for Research on Aging, Novato, CA, United States
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Kim YJ, Yoo JY, Kim OS, Kim HB, Ryu J, Kim HS, Lee JH, Yoo HI, Song DY, Baik TK, Woo RS. Neuregulin 1 regulates amyloid precursor protein cell surface expression and non-amyloidogenic processing. J Pharmacol Sci 2018; 137:146-153. [DOI: 10.1016/j.jphs.2018.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 05/06/2018] [Accepted: 05/17/2018] [Indexed: 01/11/2023] Open
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Liu XJ, Wei J, Shang YH, Huang HC, Lao FX. Modulation of AβPP and GSK3β by Endoplasmic Reticulum Stress and Involvement in Alzheimer's Disease. J Alzheimers Dis 2018; 57:1157-1170. [PMID: 28339396 DOI: 10.3233/jad-161111] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease (AD) is a dementia disease with neuronal loss and synaptic impairment. This impairment is caused, at least partly, by the generation of two main AD hallmarks, namely the hyperphosphorylated tau protein comprising neurofibrillary tangles and senile plaques containing amyloid-β (Aβ) peptides. The amyloid-β protein precursor (AβPP) and glycogen synthase kinase-3β (GSK3β) are two main proteins associated with AD and are closely correlated with these hallmarks. Recently, both of the proteins were reported to be modulated by endoplasmic reticulum stress (ERS) and are involved in the pathogenesis of AD. The mechanism of ERS plus the modulation of AβPP processing and GSK3β activity by ERS in AD are summarized and explored in this review.
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Affiliation(s)
- Xin-Jun Liu
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, P.R. China.,College of Arts and Science of Beijing Union University, Beijing, P.R. China
| | - Jun Wei
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, P.R. China.,College of Arts and Science of Beijing Union University, Beijing, P.R. China
| | - Ying-Hui Shang
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, P.R. China.,College of Arts and Science of Beijing Union University, Beijing, P.R. China
| | - Han-Chang Huang
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, P.R. China.,College of Arts and Science of Beijing Union University, Beijing, P.R. China
| | - Feng-Xue Lao
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, P.R. China.,College of Arts and Science of Beijing Union University, Beijing, P.R. China
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Ntsapi C, Lumkwana D, Swart C, du Toit A, Loos B. New Insights Into Autophagy Dysfunction Related to Amyloid Beta Toxicity and Neuropathology in Alzheimer's Disease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 336:321-361. [DOI: 10.1016/bs.ircmb.2017.07.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Soluble Conformers of Aβ and Tau Alter Selective Proteins Governing Axonal Transport. J Neurosci 2017; 36:9647-58. [PMID: 27629715 DOI: 10.1523/jneurosci.1899-16.2016] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 07/31/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Despite the demonstration that amyloid-β (Aβ) can trigger increased tau phosphorylation and neurofibrillary tangle (NFT) formation in vivo, the molecular link associating Aβ and tau pathologies remains ill defined. Here, we observed that exposure of cultured primary neurons to Aβ trimers isolated from brain tissue of subjects with Alzheimer's disease led to a specific conformational change of tau detected by the antibody Alz50. A similar association was supported by postmortem human brain analyses. To study the role of Aβ trimers in vivo, we created a novel bigenic Tg-Aβ+Tau mouse line by crossing Tg2576 (Tg-Aβ) and rTg4510 (Tg-Tau) mice. Before neurodegeneration and amyloidosis, apparent Aβ trimers were increased by ∼2-fold in 3-month-old Tg-Aβ and Tg-Aβ+Tau mice compared with younger mice, whereas soluble monomeric Aβ levels were unchanged. Under these conditions, the expression of soluble Alz50-tau conformers rose by ∼2.2-fold in the forebrains of Tg-Aβ+Tau mice compared with nontransgenic littermates. In parallel, APP accumulated intracellularly, suggestive of a putative dysfunction of anterograde axonal transport. We found that the protein abundance of the kinesin-1 light chain (KLC1) was reduced selectively in vivo and in vitro when soluble Aβ trimers/Alz50-tau were present. Importantly, the reduction in KLC1 was prevented by the intraneuronal delivery of Alz50 antibodies. Collectively, our findings reveal that specific soluble conformers of Aβ and tau cooperatively disrupt axonal transport independently from plaques and tangles. Finally, these results suggest that not all endogenous Aβ oligomers trigger the same deleterious changes and that the role of each assembly should be considered separately. SIGNIFICANCE STATEMENT The mechanistic link between amyloid-β (Aβ) and tau, the two major proteins composing the neuropathological lesions detected in brain tissue of Alzheimer's disease subjects, remains unclear. Here, we report that the trimeric Aβ species induce a pathological modification of tau in cultured neurons and in bigenic mice expressing Aβ and human tau. This linkage was also observed in postmortem brain tissue from subjects with mild cognitive impairment, when Aβ trimers are abundant. Further, this modification of tau was associated with the intracellular accumulation of the precursor protein of Aβ, APP, as a result of the selective decrease in kinesin light chain 1 expression. Our findings suggest that Aβ trimers might cause axonal transport deficits in AD.
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Activation of Ras-ERK Signaling and GSK-3 by Amyloid Precursor Protein and Amyloid Beta Facilitates Neurodegeneration in Alzheimer's Disease. eNeuro 2017; 4:eN-NWR-0149-16. [PMID: 28374012 PMCID: PMC5367084 DOI: 10.1523/eneuro.0149-16.2017] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 02/23/2017] [Accepted: 02/26/2017] [Indexed: 02/01/2023] Open
Abstract
It is widely accepted that amyloid β (Aβ) generated from amyloid precursor protein (APP) oligomerizes and fibrillizes to form neuritic plaques in Alzheimer’s disease (AD), yet little is known about the contribution of APP to intracellular signaling events preceding AD pathogenesis. The data presented here demonstrate that APP expression and neuronal exposure to oligomeric Aβ42 enhance Ras/ERK signaling cascade and glycogen synthase kinase 3 (GSK-3) activation. We find that RNA interference (RNAi)-directed knockdown of APP in B103 rat neuroblastoma cells expressing APP inhibits Ras-ERK signaling and GSK-3 activation, indicating that APP acts upstream of these signal transduction events. Both ERK and GSK-3 are known to induce hyperphosphorylation of tau and APP at Thr668, and our findings suggest that aberrant signaling by APP facilitates these events. Supporting this notion, analysis of human AD brain samples showed increased expression of Ras, activation of GSK-3, and phosphorylation of APP and tau, which correlated with Aβ levels in the AD brains. Furthermore, treatment of primary rat neurons with Aβ recapitulated these events and showed enhanced Ras-ERK signaling, GSK-3 activation, upregulation of cyclin D1, and phosphorylation of APP and tau. The finding that Aβ induces Thr668 phosphorylation on APP, which enhances APP proteolysis and Aβ generation, denotes a vicious feedforward mechanism by which APP and Aβ promote tau hyperphosphorylation and neurodegeneration in AD. Based on these results, we hypothesize that aberrant proliferative signaling by APP plays a fundamental role in AD neurodegeneration and that inhibition of this would impede cell cycle deregulation and neurodegeneration observed in AD.
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BDNF trafficking and signaling impairment during early neurodegeneration is prevented by moderate physical activity. IBRO Rep 2016; 1:19-31. [PMID: 30135925 PMCID: PMC6084862 DOI: 10.1016/j.ibror.2016.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 08/18/2016] [Accepted: 08/29/2016] [Indexed: 12/16/2022] Open
Abstract
Physical exercise can attenuate the effects of aging on the central nervous system by increasing the expression of neurotrophins such as brain-derived neurotrophic factor (BDNF), which promotes dendritic branching and enhances synaptic machinery, through interaction with its receptor TrkB. TrkB receptors are synthesized in the cell body and are transported to the axonal terminals and anchored to plasma membrane, through SLP1, CRMP2 and Rab27B, associated with KIF1B. Retrograde trafficking is made by EDH-4 together with dynactin and dynein molecular motors. In the present study it was found that early neurodegeneration is accompanied by decrease in BDNF signaling, in the absence of hyperphosphorylated tau aggregation, in hippocampus of 11 months old Lewis rats exposed to rotenone. It was also demonstrated that moderate physical activity (treadmill running, during 6 weeks, concomitant to rotenone exposure) prevents the impairment of BDNF system in aged rats, which may contribute to delay neurodegeneration. In conclusion, decrease in BDNF and TrkB vesicles occurs before large aggregate-like p-Tau are formed and physical activity applied during early neurodegeneration may be of relevance to prevent BDNF system decay.
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Nam W, Epureanu BI. Effects of Obstacles on the Dynamics of Kinesins, Including Velocity and Run Length, Predicted by a Model of Two Dimensional Motion. PLoS One 2016; 11:e0147676. [PMID: 26808534 PMCID: PMC4726810 DOI: 10.1371/journal.pone.0147676] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/06/2016] [Indexed: 02/07/2023] Open
Abstract
Kinesins are molecular motors which walk along microtubules by moving their heads to different binding sites. The motion of kinesin is realized by a conformational change in the structure of the kinesin molecule and by a diffusion of one of its two heads. In this study, a novel model is developed to account for the 2D diffusion of kinesin heads to several neighboring binding sites (near the surface of microtubules). To determine the direction of the next step of a kinesin molecule, this model considers the extension in the neck linkers of kinesin and the dynamic behavior of the coiled-coil structure of the kinesin neck. Also, the mechanical interference between kinesins and obstacles anchored on the microtubules is characterized. The model predicts that both the kinesin velocity and run length (i.e., the walking distance before detaching from the microtubule) are reduced by static obstacles. The run length is decreased more significantly by static obstacles than the velocity. Moreover, our model is able to predict the motion of kinesin when other (several) motors also move along the same microtubule. Furthermore, it suggests that the effect of mechanical interaction/interference between motors is much weaker than the effect of static obstacles. Our newly developed model can be used to address unanswered questions regarding degraded transport caused by the presence of excessive tau proteins on microtubules.
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Affiliation(s)
- Woochul Nam
- University of Michigan, Ann Arbor, Michigan 48109-2125, United States of America
| | - Bogdan I Epureanu
- University of Michigan, Ann Arbor, Michigan 48109-2125, United States of America
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12
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Muresan V, Ladescu Muresan Z. Shared Molecular Mechanisms in Alzheimer's Disease and Amyotrophic Lateral Sclerosis: Neurofilament-Dependent Transport of sAPP, FUS, TDP-43 and SOD1, with Endoplasmic Reticulum-Like Tubules. NEURODEGENER DIS 2015; 16:55-61. [PMID: 26605911 DOI: 10.1159/000439256] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 08/07/2015] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Amyotrophic lateral sclerosis (ALS), a debilitating neurodegenerative disorder of the motor neurons, leads to the disorganization of the neurofilament (NF) cytoskeleton and - ultimately - the deterioration of the neuromuscular junction. Some familial cases of ALS are caused by mutated FUS, TDP-43 or SOD1; it is thought that the mutated proteins inflict pathology either by gain or loss of function. The proper function of the neuromuscular junction requires sAPP, a soluble proteolytic fragment of the amyloid-β precursor protein (APP) - a transmembrane protein implicated in the pathology of Alzheimer's disease (AD). Whether sAPP, FUS, TDP-43 and SOD1 are mechanistically linked in a common pathway deregulated in both AD and ALS is not known. SUMMARY We show that sAPP, TDP-43, FUS and SOD1 are transported to neurite terminals by a mechanism that involves endoplasmic reticulum (ER)-like tubules and requires peripherin NFs. The transport of these proteins, and the translocation of the ER protein reticulon 4 (Rtn4) into neurites was studied in CAD cells, a brainstem-derived neuronal cell line highly relevant to AD and ALS. We show that a significant fraction of sAPP is generated in the soma and accumulates in a juxtanuclear ER subdomain. In neurites, sAPP localizes to Rtn4-positive ER-like tubules that extend from the soma into the growth cone and colocalizes with peripherin NFs. Knocking down peripherin disrupts the NF network and diminishes the accumulation of sAPP, TDP-43, FUS, SOD1 and Rtn4 at terminals. KEY MESSAGES We propose that the impediment of a common, ER-mediated mechanism of transport of sAPP, TDP-43, FUS and SOD1, caused by a disrupted NF network, could be part of the mechanisms leading to AD and ALS.
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Affiliation(s)
- Virgil Muresan
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, N.J., USA
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13
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Muresan V, Ladescu Muresan Z. Amyloid-β precursor protein: Multiple fragments, numerous transport routes and mechanisms. Exp Cell Res 2015; 334:45-53. [PMID: 25573596 DOI: 10.1016/j.yexcr.2014.12.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 12/26/2014] [Indexed: 02/01/2023]
Abstract
This review provides insight into the intraneuronal transport of the Amyloid-β Precursor Protein (APP), the prototype of an extensively posttranslationally modified and proteolytically cleaved transmembrane protein. Uncovering the intricacies of APP transport proves to be a challenging endeavor of cell biology research, deserving increased priority, since APP is at the core of the pathogenic process in Alzheimer's disease. After being synthesized in the endoplasmic reticulum in the neuronal soma, APP enters the intracellular transport along the secretory, endocytic, and recycling routes. Along these routes, APP undergoes cleavage into defined sets of fragments, which themselves are transported - mostly independently - to distinct sites in neurons, where they exert their functions. We review the currently known routes and mechanisms of transport of full-length APP, and of APP fragments, commenting largely on the experimental challenges posed by studying transport of extensively cleaved proteins. The review emphasizes the interrelationships between the proteolytic and posttranslational modifications, the intracellular transport, and the functions of the APP species. A goal remaining to be addressed in the future is the incorporation of the various views on APP transport into a coherent picture. In this review, the disease context is only marginally addressed; the focus is on the basic biology of APP transport under normal conditions. As shown, the studies of APP transport uncovered numerous mechanisms of transport, some of them conventional, and others, novel, awaiting exploration.
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Affiliation(s)
- Virgil Muresan
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07101-1709, USA.
| | - Zoia Ladescu Muresan
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07101-1709, USA.
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14
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Effects of the neurotrophic agent T-817MA on oligomeric amyloid-β–induced deficits in long-term potentiation in the hippocampal CA1 subfield. Neurobiol Aging 2014; 35:532-6. [DOI: 10.1016/j.neurobiolaging.2013.08.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 08/23/2013] [Accepted: 08/30/2013] [Indexed: 12/13/2022]
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15
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Tau causes synapse loss without disrupting calcium homeostasis in the rTg4510 model of tauopathy. PLoS One 2013; 8:e80834. [PMID: 24278327 PMCID: PMC3835324 DOI: 10.1371/journal.pone.0080834] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/15/2013] [Indexed: 01/23/2023] Open
Abstract
Neurofibrillary tangles (NFTs) of tau are one of the defining hallmarks of Alzheimer’s disease (AD), and are closely associated with neuronal degeneration. Although it has been suggested that calcium dysregulation is important to AD pathogenesis, few studies have probed the link between calcium homeostasis, synapse loss and pathological changes in tau. Here we test the hypothesis that pathological changes in tau are associated with changes in calcium by utilizing in vivo calcium imaging in adult rTg4510 mice that exhibit severe tau pathology due to over-expression of human mutant P301L tau. We observe prominent dendritic spine loss without disruptions in calcium homeostasis, indicating that tangles do not disrupt this fundamental feature of neuronal health, and that tau likely induces spine loss in a calcium-independent manner.
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16
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Villegas C, Muresan V, Ladescu Muresan Z. Dual-tagged amyloid-β precursor protein reveals distinct transport pathways of its N- and C-terminal fragments. Hum Mol Genet 2013; 23:1631-43. [PMID: 24203698 DOI: 10.1093/hmg/ddt555] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The amyloid-β precursor protein (APP), a type I transmembrane protein genetically associated with Alzheimer's disease, has a complex biology that includes proteolytic processing into potentially toxic fragments, extensive trafficking and multiple, yet poorly-defined functions. We recently proposed that a significant fraction of APP is proteolytically cleaved in the neuronal soma into N- and C-terminal fragments (NTFs and CTFs), which then target independently of each other to separate destinations in the cell. Here, we prove this concept with live imaging and immunolocalization of two dual, N- and C-termini-tagged APP constructs: CFP-APP-YFP [containing the fluorescent tags, cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP)] and FLAG-APP-Myc. When expressed at low levels in neuronal cells, these constructs are processed into differently tagged NTFs and CTFs that reveal distinct distributions and characteristics of transport. Like the endogenous N- and C-terminal epitopes of APP, the FLAG-tagged NTFs are present in trains of vesicles and tubules that localize to short filaments, which often immunostain for acetylated tubulin, whereas the Myc-tagged CTFs are detected on randomly distributed vesicle-like structures. The experimental treatments that selectively destabilize the acetylated microtubules abrogate the distribution of NTFs along filaments, without altering the random distribution of CTFs. These results indicate that the NTFs and CTFs are recruited to distinct transport pathways and reach separate destinations in neurons, where they likely accomplish functions independent of the parental, full-length APP. They also point to a compartment associated with acetylated microtubules in the neuronal soma--not the neurite terminals--as a major site of APP cleavage, and segregation of NTFs from CTFs.
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Affiliation(s)
- Christine Villegas
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07101-1709, USA
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17
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Muresan V, Villegas C, Ladescu Muresan Z. Functional interaction between amyloid-β precursor protein and peripherin neurofilaments: a shared pathway leading to Alzheimer's disease and amyotrophic lateral sclerosis? NEURODEGENER DIS 2013; 13:122-5. [PMID: 24009040 DOI: 10.1159/000354238] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 07/06/2013] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND OBJECTIVE The pathology of amyotrophic lateral sclerosis (ALS), a neurodegenerative disorder affecting motor neurons, comprises aberrant accumulations of neurofilaments; mutations in the peripherin subunit of neurofilaments have been identified in some forms of ALS. Recently, the amyloid-β precursor protein (APP), a key element for the pathology of Alzheimer's disease (AD), was linked to ALS. Here, we provide evidence that the generation of the N-terminal fragment of APP, sAPP, relies on peripherin neurofilaments. This finding could relate to a novel molecular mechanism dysregulated in ALS and/or AD. METHODS AND RESULTS The production and the fate of sAPP were studied with the brainstem-derived, neuronal cell line, CAD, which expresses endogenous peripherin. We show that sAPP and C-terminal fragments (CTF) are generated to a large extent in the neuronal soma. We find that sAPP, but not CTF, associates with filamentous structures that delineate the nuclear lamina, extend to the cell periphery and immunostain for peripherin. The depletion of peripherin with siRNA eliminates the filamentous immunostaining of sAPP. CONCLUSION Our results indicate that a fraction of APP is cleaved by β-secretase in the soma and that the generated sAPP becomes associated with perinuclear peripherin neurofilaments. These findings link the metabolism of APP--which is dysregulated in AD--to the organization of neurofilaments--which is abnormal in ALS--and suggest a possible crosstalk/overlap between the molecular mechanisms of these diseases.
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Affiliation(s)
- Virgil Muresan
- Department of Pharmacology and Physiology, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, N.J., USA
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18
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Bearer EL. HSV, axonal transport and Alzheimer's disease: in vitro and in vivo evidence for causal relationships. Future Virol 2012; 7:885-899. [PMID: 23335944 DOI: 10.2217/fvl.12.81] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
HSV, a neurotropic virus, travels within neuronal processes by fast axonal transport. During neuronal infection HSV travels retrograde from the sensory nerve terminus to the neuronal cell body, where it replicates or enters latency. During replication HSV travels anterograde from the cell body to the nerve terminus. Postmortem studies find a high frequency of HSV DNA in the trigeminal ganglia as well as the brain. Studies correlating HSV with Alzheimer's disease (AD) have been controversial. Here we review clinical evidence supporting such a link. Furthermore, the author describes experimental data showing physical interactions between nascent HSV particles and host transport machinery implicated in AD. The author concludes that the complexity of this relationship has been insufficiently explored, although the relative ease and nontoxicity of a potential anti-HSV treatment for AD demands further study.
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Affiliation(s)
- Elaine L Bearer
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 81131, USA
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19
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Posse de Chaves E. Reciprocal regulation of cholesterol and beta amyloid at the subcellular level in Alzheimer's disease. Can J Physiol Pharmacol 2012; 90:753-64. [PMID: 22626060 DOI: 10.1139/y2012-076] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Since the discovery that apolipoprotein E, a cholesterol transport protein, is a major risk factor for Alzheimer's disease (AD) development, there has been a remarkable interest in understanding the many facets of the relationship between cholesterol and AD. Several lines of evidence have demonstrated the importance of cholesterol in amyloid beta peptide (Aβ) production and metabolism, as well as the involvement of Aβ in cholesterol homeostasis. The emerging picture is complex and still incomplete. This review discusses findings that indicate that a reciprocal regulation exists between Aβ and cholesterol at the subcellular level. The pathological impact of such regulation is highlighted.
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Affiliation(s)
- Elena Posse de Chaves
- Department of Pharmacology, 9-31 Medical Sciences Building, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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20
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Lee DY, Fletcher E, Carmichael OT, Singh B, Mungas D, Reed B, Martinez O, Buonocore MH, Persianinova M, Decarli C. Sub-Regional Hippocampal Injury is Associated with Fornix Degeneration in Alzheimer's Disease. Front Aging Neurosci 2012; 4:1. [PMID: 22514534 PMCID: PMC3323836 DOI: 10.3389/fnagi.2012.00001] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 03/11/2012] [Indexed: 02/04/2023] Open
Abstract
We examined in vivo evidence of axonal degeneration in association with neuronal pathology in Alzheimer's disease (AD) through analysis of fornix microstructural integrity and measures of hippocampal subfield atrophy. Based on known anatomical topography, we hypothesized that the local thickness of subiculum and CA1 hippocampus fields would be associated with fornix integrity, reflecting an association between AD-related injury to hippocampal neurons and degeneration of associated axon fibers. To test this hypothesis, multi-modal imaging, combining measures of local hippocampal radii with diffusion tensor imaging (DTI), was applied to 44 individuals clinically diagnosed with AD, 44 individuals clinically diagnosed with mild cognitive impairment (MCI), and 96 cognitively normal individuals. Fornix microstructural degradation, as measured by reduced DTI-based fractional anisotropy (FA), was prominent in both MCI and AD, and was associated with reduced hippocampal volumes. Further, reduced fornix FA was associated with reduced anterior CA1 and antero-medial subiculum thickness. Finally, while both lesser fornix FA and lesser hippocampal volume were associated with lesser episodic memory, only the hippocampal measures were significant predictors of episodic memory in models including both hippocampal and fornix predictors. The region-specific association between fornix integrity and hippocampal neuronal death may provide in vivo evidence for degenerative white matter injury in AD: axonal pathology that is closely linked to neuronal injury.
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Affiliation(s)
- Dong Young Lee
- Imaging of Dementia and Aging Laboratory, Department of Neurology, Center for Neuroscience, University of California at Davis Davis, CA, USA
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21
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Goldstein LSB. Axonal transport and neurodegenerative disease: can we see the elephant? Prog Neurobiol 2012; 99:186-90. [PMID: 22484448 DOI: 10.1016/j.pneurobio.2012.03.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 03/18/2012] [Accepted: 03/20/2012] [Indexed: 01/07/2023]
Abstract
Although it is well established that axonal transport defects are part of the initiation or progression of some neurodegenerative diseases, the precise role of these defects in disease development is poorly understood. Thus, in this article, rather than enumerate the already well-reviewed evidence that there are transport deficits in disease, I will focus on a discussion of two crucial and unanswered questions about the possible role of axonal transport defects in HD and AD. (1) Are alterations in axonal transport caused by changes in the normal function of proteins mutated or altered in HD and AD and/or do such alterations in transport occur as a result of the formation of toxic aggregates of peptides or proteins? (2) Do alterations in axonal transport contribute to the causes of HD and AD or are they early, or late, secondary consequences of other cellular defects caused by disease-induction?
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Affiliation(s)
- Lawrence S B Goldstein
- Department of Cellular and Molecular Medicine and Department of Neurosciences, UCSD School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0695, USA.
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22
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Muresan V, Muresan Z. Unconventional functions of microtubule motors. Arch Biochem Biophys 2012; 520:17-29. [PMID: 22306515 PMCID: PMC3307959 DOI: 10.1016/j.abb.2011.12.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 12/21/2011] [Accepted: 12/23/2011] [Indexed: 11/21/2022]
Abstract
With the functional characterization of proteins advancing at fast pace, the notion that one protein performs different functions - often with no relation to each other - emerges as a novel principle of how cells work. Molecular motors are no exception to this new development. Here, we provide an account on recent findings revealing that microtubule motors are multifunctional proteins that regulate many cellular processes, in addition to their main function in transport. Some of these functions rely on their motor activity, but others are independent of it. Of the first category, we focus on the role of microtubule motors in organelle biogenesis, and in the remodeling of the cytoskeleton, especially through the regulation of microtubule dynamics. Of the second category, we discuss the function of microtubule motors as static anchors of the cargo at the destination, and their participation in regulating signaling cascades by modulating interactions between signaling proteins, including transcription factors. We also review atypical forms of transport, such as the cytoplasmic streaming in the oocyte, and the movement of cargo by microtubule fluctuations. Our goal is to provide an overview of these unexpected functions of microtubule motors, and to incite future research in this expanding field.
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Affiliation(s)
- Virgil Muresan
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, U.S.A
| | - Zoia Muresan
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, U.S.A
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23
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Xiao AW, He J, Wang Q, Luo Y, Sun Y, Zhou YP, Guan Y, Lucassen PJ, Dai JP. The origin and development of plaques and phosphorylated tau are associated with axonopathy in Alzheimer's disease. Neurosci Bull 2012; 27:287-99. [PMID: 21934724 DOI: 10.1007/s12264-011-1736-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
OBJECTIVE The production of neurotoxic β-amyloid and the formation of hyperphosphorylated tau are thought to be critical steps contributing to the neuropathological mechanisms in Alzheimer's disease (AD). However, there remains an argument as to their importance in the onset of AD. Recent studies have shown that axonopathy is considered as an early stage of AD. However, the exact relationship between axonopathy and the origin and development of classic neuropathological changes such as senile plaques (SPs) and neurofibrillary tangles (NFTs) is unclear. The present study aimed to investigate this relationship. METHODS Postmortem tracing, combined with the immunohistochemical or immunofluorescence staining, was used to detect axonopathy and the formation of SPs and NFTs. RESULTS Axonal leakage-a novel type of axonopathy, was usually accompanied with the extensive swollen axons and varicosities, and was associated with the origin and development of Aβ plaques and hyperphosphorylated tau in the brains of AD patients. CONCLUSION Axonopathy, particularly axonal leakage, might be a key event in the initiation of the neuropathological processes in AD.
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Affiliation(s)
- Ai-Wu Xiao
- Wuhan Institute for Neuroscience and Neuroengineering, South-Central University for Nationalities, Wuhan 430074, China
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Skaper SD. Alzheimer's disease and amyloid: culprit or coincidence? INTERNATIONAL REVIEW OF NEUROBIOLOGY 2012; 102:277-316. [PMID: 22748834 DOI: 10.1016/b978-0-12-386986-9.00011-9] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Alzheimer's disease (AD) is the largest unmet medical need in neurology today. This most common form of irreversible dementia is placing a considerable and increasing burden on patients, caregivers, and society, as more people live long enough to become affected. Current drugs improve symptoms but do not have profound neuroprotective and/or disease-modifying effects. AD is characterized by loss of neurons, dystrophic neurites, senile/amyloid/neuritic plaques, neurofibrillary tangles, and synaptic loss. Beta-amyloid (Aβ) peptide deposition is the major pathological feature of AD. Increasing evidence suggests that overexpression of the amyloid precursor protein and subsequent generation of the 39-43 amino acid residue, Aβ, are central to neuronal degeneration observed in AD patients possessing familial AD mutations, while transgenic mice overexpressing amyloid precursor protein develop AD-like pathology. Despite the genetic and cell biological evidence that supports the amyloid hypothesis, it is becoming increasing clear that AD etiology is complex and that Aβ alone is unable to account for all aspects of AD. The fact that vast overproduction of Aβ peptides in the brain of transgenic mouse models fails to cause overt neurodegeneration raises the question as to whether accumulation of Aβ peptides is indeed the culprit for neurodegeneration in AD. There is increasing evidence to suggest that Aβ/amyloid-independent factors, including the actions of AD-related genes (microtubule-associated protein tau, polymorphisms of apolipoprotein E4), inflammation, and oxidative stress, also contribute to AD pathogenesis. This chapter reviews the current state of knowledge on these factors and their possible interactions, as well as their potential for neuroprotection targets.
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Affiliation(s)
- Stephen D Skaper
- Department of Pharmacology and Anesthesiology, University of Padova, Largo E. Meneghetti, Padova, Italy
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25
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Abstract
Accumulation of neurofibrillary tangles (NFT), intracellular inclusions of fibrillar forms of tau, is a hallmark of Alzheimer Disease. NFT have been considered causative of neuronal death, however, recent evidence challenges this idea. Other species of tau, such as soluble misfolded, hyperphosphorylated, and mislocalized forms, are now being implicated as toxic. Here we review the data supporting soluble tau as toxic to neurons and synapses in the brain and the implications of these data for development of therapeutic strategies for Alzheimer's disease and other tauopathies.
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Muresan V, Muresan Z. A persistent stress response to impeded axonal transport leads to accumulation of amyloid-β in the endoplasmic reticulum, and is a probable cause of sporadic Alzheimer's disease. NEURODEGENER DIS 2011; 10:60-3. [PMID: 22156573 DOI: 10.1159/000332815] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 09/03/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND AND OBJECTIVE Could a normal--but persistent--stress response to impeded axonal transport lead to late-onset Alzheimer's disease (AD)? Our results offer an affirmative answer, suggesting a mechanism for the abnormal production of amyloid-β (Aβ), triggered by the slowed axonal transport at old age. We hypothesize that Aβ precursor protein (APP) is a sensor at the endoplasmic reticulum (ER) that detects, and signals to the nucleus, abnormalities in axonal transport. When persistently activated, due to chronically slowed-down transport, this signaling pathway leads to accumulation of Aβ within the ER. METHODS AND RESULTS We tested this hypothesis with the neuronal cell line CAD. We show that, normally, a fraction of APP is transported into neurites by recruiting kinesin-1 via the adaptor protein, Fe65. Under conditions that block kinesin-1-dependent transport, APP, Fe65 and kinesin-1 accumulate in the soma, and form a complex at the ER. This complex recruits active c-Jun N-terminal kinase (JNK), which phosphorylates APP at Thr(668). This phosphorylation increases the cleavage of APP by the amyloidogenic pathway, which generates Aβ within the ER lumen, and releases Fe65 into the cytoplasm. Part of the released Fe65 translocates into the nucleus, likely to initiate a gene transcription response to arrested transport. Prolonged arrest of kinesin-1-dependent transport could thus lead to accumulation and oligomerization of Aβ in the ER. CONCLUSION These results support a model where the APP:Fe65 complex is a sensor at the ER for detecting the increased level of kinesin-1 caused by halted transport, which signals to the nucleus, while concomitantly generating an oligomerization-prone pool of Aβ in the ER. Our hypothesis could thus explain a pathogenic mechanism in AD.
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Affiliation(s)
- Virgil Muresan
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, NJ 07101-1709, USA
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27
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Kopeikina KJ, Carlson GA, Pitstick R, Ludvigson AE, Peters A, Luebke JI, Koffie RM, Frosch MP, Hyman BT, Spires-Jones TL. Tau accumulation causes mitochondrial distribution deficits in neurons in a mouse model of tauopathy and in human Alzheimer's disease brain. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:2071-82. [PMID: 21854751 DOI: 10.1016/j.ajpath.2011.07.004] [Citation(s) in RCA: 194] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 06/20/2011] [Accepted: 07/01/2011] [Indexed: 01/12/2023]
Abstract
Neurofibrillary tangles (NFT), intracellular inclusions of abnormal fibrillar forms of microtubule associated protein tau, accumulate in Alzheimer's disease (AD) and other tauopathies and are believed to cause neuronal dysfunction, but the mechanism of tau-mediated toxicity are uncertain. Tau overexpression in cell culture impairs localization and trafficking of organelles. Here we tested the hypothesis that, in the intact brain, changes in mitochondrial distribution occur secondary to pathological changes in tau. Array tomography, a high-resolution imaging technique, was used to examine mitochondria in the reversible transgenic (rTg)4510, a regulatable transgenic, mouse model and AD brain tissue. Mitochondrial distribution is progressively disrupted with age in rTg4510 brain, particularly in somata and neurites containing Alz50-positive tau aggregates. Suppression of soluble tau expression with doxycycline resulted in complete recovery of mitochondrial distribution, despite the continued presence of aggregated tau. The effect on mitochondrial distribution occurs without concomitant alterations in neuropil mitochondrial size, as assessed by both array tomography and electron microscopy. Similar mitochondrial localization alterations were also observed in human AD tissue in Alz50+ neurons, confirming the relevance of tau to mitochondrial trafficking observed in this animal model. Because abnormalities reverted to normal if soluble tau was suppressed in rTg4510 mice, even in the continued presence of fibrillar tau inclusions, we suggest that soluble tau plays an important role in mitochondrial abnormalities, which likely contribute to neuronal dysfunction in AD.
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Affiliation(s)
- Katherine J Kopeikina
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown Massachusetts, Charlestown, MA 02129, USA
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Microstructural alteration of the anterior cingulum is associated with apathy in Alzheimer disease. Am J Geriatr Psychiatry 2011; 19:644-53. [PMID: 21709610 DOI: 10.1097/jgp.0b013e31820dcc73] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES To identify regional alterations of white matter integrity associated with apathy in Alzheimer disease (AD). DESIGN Cross-sectional study. SETTING University Dementia Clinic. PARTICIPANTS Fifty-one very mild or mild probable AD subjects. INTERVENTION Volumetric magnetic resonance imaging with diffusion tensor imaging. MEASUREMENTS Volume of interest analyses were performed to compare regional fractional anisotropy (FA) between apathy and apathy-free group, and to test linear relationship between regional FA and apathy severity. Apathy was assessed by the Neuropsychiatric Inventory. RESULTS Apathy group showed significantly lower FA values than apathy-free group in the left anterior cingulum (A-C), regardless of concomitant depression and psychotropic medications. Left A-C FA values also had significant linear relationship with apathy-composite scores as a measure of apathy severity, even after controlling gray matter density of the ipsilateral anterior cingulate cortex. CONCLUSIONS Our findings support that communication failure between the anterior cingulate cortex and other brain structures via the A-C contributes to the development and aggravation of apathy in AD, additionally supporting the general notion of disconnection syndrome for clinical manifestation of AD.
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Smith KDB, Paylor R, Pautler RG. R-flurbiprofen improves axonal transport in the Tg2576 mouse model of Alzheimer's disease as determined by MEMRI. Magn Reson Med 2010; 65:1423-9. [PMID: 21500269 DOI: 10.1002/mrm.22733] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 09/28/2010] [Accepted: 10/27/2010] [Indexed: 12/18/2022]
Abstract
Axonal pathology is a prevalent feature of Alzheimer's disease (AD) and is thought to occur predominantly due to the accumulation of amyloid beta (Aβ). However, it remains unclear whether therapeutics geared toward reducing Aβ improves axonal deficits. We have previously used Manganese Enhanced MRI to demonstrate that axonal transport deficits occur before plaque formation in the Tg2576 mouse model of Alzheimer's disease. Here we tested whether axonal transport deficits in the Tg2576 mouse model improve in response to the Aβ42 selective lowering agent R-Flurbiprofen (R-F). We demonstrated that in young animals (before Aβ plaque formation), R-F treatment reduced Aβ42 levels and coincided with a significant improvement in axonal transport (P = 0.0186). However, in older animals (after plaque formation had occurred), we observed that R-F treatment did not reduce Aβ42 levels although we still observed a significant improvement in axonal transport as assessed with MEMRI (P = 0.0329). We then determined that R-F treatment reduced tau hyper-phosphorylation in the older animals. These data indicate that both Aβ42 and tau comprise a role in axonal transport rate deficits in the Tg2576 model of Alzheimer's Disease.
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Affiliation(s)
- Karen D B Smith
- Dept. Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, USA
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Amyloid-beta peptide oligomers disrupt axonal transport through an NMDA receptor-dependent mechanism that is mediated by glycogen synthase kinase 3beta in primary cultured hippocampal neurons. J Neurosci 2010; 30:9166-71. [PMID: 20610750 DOI: 10.1523/jneurosci.1074-10.2010] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Disruption of axonal transport is a hallmark of several neurodegenerative diseases, including Alzheimer's disease (AD). Even though defective transport is considered an early pathologic event, the mechanisms by which neurodegenerative insults impact transport are poorly understood. We show that soluble oligomers of the amyloid-beta peptide (AbetaOs), increasingly recognized as the proximal neurotoxins in AD pathology, induce disruption of organelle transport in primary hippocampal neurons in culture. Live imaging of fluorescent protein-tagged organelles revealed a marked decrease in axonal trafficking of dense-core vesicles and mitochondria in the presence of 0.5 microm AbetaOs. NMDA receptor (NMDAR) antagonists, including d-AP5, MK-801, and memantine, prevented the disruption of trafficking, thereby identifying signals for AbetaO action at the cell membrane. Significantly, both pharmacological inhibition of glycogen synthase kinase-3beta (GSK-3beta) and transfection of neurons with a kinase-dead form of GSK-3beta prevented the transport defect. Finally, we demonstrate by biochemical and immunocytochemical means that AbetaOs do not affect microtubule stability, indicating that disruption of transport involves a more subtle mechanism than microtubule destabilization, likely the dysregulation of intracellular signaling cascades. Results demonstrate that AbetaOs negatively impact axonal transport by a mechanism that is initiated by NMDARs and mediated by GSK-3beta and establish a new connection between toxic Abeta oligomers and AD pathology.
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Perlson E, Maday S, Fu MM, Moughamian AJ, Holzbaur ELF. Retrograde axonal transport: pathways to cell death? Trends Neurosci 2010; 33:335-44. [PMID: 20434225 DOI: 10.1016/j.tins.2010.03.006] [Citation(s) in RCA: 249] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 03/22/2010] [Accepted: 03/26/2010] [Indexed: 12/11/2022]
Abstract
Active transport along the axon is crucial to the neuron. Motor-driven transport supplies the distal synapse with newly synthesized proteins and lipids, and clears damaged or misfolded proteins. Microtubule motors also drive long-distance signaling along the axon via signaling endosomes. Although positive signaling initiated by neurotrophic factors has been well-studied, recent research has focused on stress-signaling along the axon. Here, the connections between axonal transport alterations and neurodegeneration are discussed, including evidence for defective transport of vesicles, mitochondria, degradative organelles, and signaling endosomes in models of amyotrophic lateral sclerosis, Huntington's, Parkinson's and Alzheimer's disease. Defects in transport are sufficient to induce neurodegeneration, but recent progress suggests that changes in retrograde signaling pathways correlate with rapidly progressive neuronal cell death.
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Affiliation(s)
- Eran Perlson
- Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19067, USA
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